This invention relates to a pressure gas engine in which high velocity gas is blasted from an arcuate series of nozzles toward the rim of a rotor that is closely adjacent to the nozzle exits. This rim at its periphery is provided with arcuate buckets into which these blasts of gas are received. Both the entrances and the exits of the buckets are located at this periphery. The gas after flowing over the arcuate surfaces of the buckets, whch are each arranged on a chord of the rim that is closely adjacent to a tangent to the rim that is parallel to the chord, passes from the bucket exits at very low back pressure so that there is a high efficiency conversion of gas velocity to rotary power.
The pressure gas engine or turbine of this invention contrasts in efficiency of power conversion to the customary reentry type of turbine. These re-entry turbines are the type disclosed in many prior patents including the following: U.S. Pat. Nos. 748,678; 751,589; 845,059; 910,428; 911,492; 979,077; 985,885; 992,433; 1,145,144; 1,546,744 and 3,197,177.
It has been discovered that by providing a straight through passage of the gas from the nozzles through the buckets and into a volumetric section of low fluid back pressure a major improvement in performance is achieved. This is true for many reasons. For example, in the re-entry impulse type of turbine where the gas flows successively through a series of re-entry stages the relative velocity of the fluid passing from one reentry stage to the next constantly decreases while the density of the gas remains constant. Consequently, as the velocity of the gas flowing through the re-entry passages and buckets decreases the cross sectional area of the gas flow increases in inverse proportion.
Attempts have been made in the past to solve this problem of increasing cross sectional area of the gas stream with decreasing speed from one re-entry stage to the next by providing an escape path for some of the gas stream before all of its kinetic energy is converted to power on the re-entry. However, this has not been satisfactory so that such re-entry stage turbines have never been very efficient. Further, the high velocity gas which actually makes a full trip through the successive re-entry stages is subject to a multitude of effects resulting from the long and tortuous path that the gas must take in the re-entry stages and the resulting improper relative angles of entry of the recirculating gas to the rotor which is traveling at constant speed. This type of path tends to convert the kinetic energy of the gas stream to heat rather than to work on rotating the rotor.
In contrast, the turbine of this invention does not subject the high velocity gas to a long path to convert its energy to shaft horsepower in the rotor but goes contrary to these prior teachings in providing the shortest possible path from the nozzles through the buckets to the exhaust area. Many tests have shown that this elmination of the re-entry stages of the prior art coupled with a corresponding increase in turbine rotor rim speed greatly improves the efficiency of the engine. This efficiency is defined as the conversion of the potential energy of the compressed gas to shaft horsepower and with the engine of this invention is much greater than has been achieved before to the best of my knowledge.